902,942. Gas-turbine plant ; axial-flow compressors. SOLAR AIRCRAFT CO. Aug. 26, 1960, No. 29504/60. Classes 110 (1) and 110 (3). A gas-turbine plant comprising an air compressor, a combustion chamber and a multistage turbine assembly arranged in series fluid communication having at least one turbine stage including a first rotor driving the compressor and at least one additional turbine stage embodying an additional rotor, mounted in axial alignment with and adjacent the first rotor, the additional rotor being independently rotatable and connected to a first power take-off shaft, has a second power take-off shaft connected to the compressor remote from the turbine assembly, first coupling means on the low pressure end face of the first rotor and second coupling means on the high pressure end face of the additional rotor for coupling this rotor to the first power take-off shaft or to the first rotor. Air from the intake 66 is compressed in the axial flow compressor 19 and discharged through a scroll 20 to a combustion chamber which supplies a turbine assembly 23 through an inlet scroll 22. The compressor carries at its discharge end a gear-box 28 through which is driven a power take-off shaft 43. The compressor outlet scroll is made of two sections, viz. an outer annular wall 31 and an inner section 32 which defines a chamber 34. A dished casting 35 secured to the compressor rotor cylinder 36 has a hub 37 supported in a roller bearing 38 mounted in the casing 33. The annular wall 49 of the gear-box 28 is provided with a plurality of radial ports 51 through which ambient air is admitted to a sheet metal duct 52 leading to bores 54 in the bearing supporting wall 39. The air is drawn in through ports 51 by a fan 55 and is discharged through passages 56 and ports 58. This circulating air cools the gear-box wall 48 and bearings 38, 45. Labyrinth seals 59 formed between the wall 39 and the dished casting seal the fan 55 from the bearing 38. The other end of the compressor rotor cylinder 36 is supported from a casting 69 by a dished casting 72 mounted in bearings 71. Labyrinth seals 76 form a seal between the wall 78 and the compressor rotor structure. The rotors 84 of the compressor are attached to the rotor cylinder 36 by means of rivets 85. Certain of the rivets have been omitted to provide bleed passages 91 so as to supply pressurized air to the labyrinth seals 59, 76 through passages 92, 93 and to cool the second stage structure as hereinafter described. Passageways 94 are provided to supply lubricant to the splined connections 42, 95a. The turbine assembly 23, Fig. 3, comprises a two-stage turbine formed by rotor discs 100, 162 driving the compressor rotor 36 through shafts 96, 98 and a single-stage turbine formed by a rotor disc 163 driving a take-off power shaft through a shaft 185. The casting 69 also supports a further turbine bearing 126 and carries a casting 119 which forms a fan chamber containing fan blades 125<SP>1</SP> formed on the upstream face of the rotor. The fan blades 125<SP>1</SP> draw air from the atmosphere and discharge it into the chamber formed between the rotor 100 and cap 123 which is turn connected to the air duct 125a surrounding the turbine scroll 22 so as to cool the rotor and shroud 125b. The inner race of the bearing 126 permits axial sliding of the bearing roller to accommodate expansion. The casting 119 also supports the inner ends of the inlet stator vanes 141 the outer ends of which are attached to the outer casing ring 142. A labyrinth seal 147 also supported by casting 119 is supplied with compressed air from the compressor discharge through ports 159, 161 and passages 153, 157. The turbine end of the tubular shaft 98 is provided with an internallythreaded annulus 154 which receives the end of a turbine rotor assembly bolt 155, the opposite end of which has a wrench head 156. The bolt 155 is prevented from unscrewing by a retaining ring 165. The rotors 100, 162 are also connected together by a recess 167 and an annular boss 168. The boss 168 is provided with notches or by seats 169 adapted to receive the base portions of T-shaped driving keys 171, the stems 172 of which extend radially outwards through keyways or notches 173 formed in flanges on the rotors 100, 162. The lowpressure end face of the turbine rotor 162 also has an axially-extending flange with annularlyspaced keyways or notches 179 forming a recess 164 surrounding the assembly bolt head. The opposing hub face of rotor 163 is provided with a similar recess 181 having notches or keyways 182. The recess 181 houses the head of a securing bolt 183 which engages an internally threaded annulus 184 welded to the power take-off shaft 185. The shaft 185 and the rotor 163 are formed respectively with a flange 173 and interfitting boss 168 similar to the corresponding parts of the rotors 100, 162 which are drivingly connected by similar keys 171. The shaft 185 is supported by bearings 126, 211 in a casing 189. A cap member 192 attached to the casing 189 has air passages 197, 198 so that atmospheric cooling air may be drawn in by the fan 207 and discharged over the rotor face and the exhaust passage 24 cooling air bled from the compressor is passed through the securing bolt 155 and over the rear face of the rotor 162 and closure cap 199 supported by the third stage stator. The cap member 192 also carries a seal ring assembly 224 which engages an annular flange 225 on the rotor 163. The turbine casing is of sectional construction and comprises a ring member 142, ring portions 135, 136 and liner ring segments 240. The succeeding sections are made up of outer casing rings 241, 242, 243 respectively provided with a stator blade assembly 244, liner segments 245, stator blade assembly 246 and liner segments 247. Pins 253 prevent relative rotation between the stator blade assemblies 244, 246 and the rings 241, 242. The casing rings 242, 243 are connected by an expansion joint 247<SP>1</SP>. A C-shaped clamping ring 276 connects the exhaust section 255 to the casing ring 243. To convert the engine to a single shaft engine, as shown in Fig. 6, the expansion joint 247<SP>1</SP> is removed and new casing section 254a, 262a substituted for the 254, 262, the casting 189 and associated shaft 185 are removed and rotor 163 connected to rotors 106, 162 by a modified assembly bolt 155a. The rotors 162, 163 are connected by a coupling ring 292, in which are seated T-shaped keys 294 which also engage notches 179, 182 in axially-extending flanges on the rotors. The cover-plate 199 is replaced by a labyrinth seal ring 291. Cooling air is supplied to the downstream face of the rotor 163 by the fan 207 supplied with air through an open-ended cylinder 301. Cooling air is supplied to the downstream face of the rotor 162 through passages 158, 161, annular chamber 298 and passages 286, 287. The engine may be arranged to provide a supply of compressed air in addition to mechanical power. The compressed air may be used for starting gas-turbine jet-propulsion engines or for supplying air to the flight deck air-conditioning system. Air from the compressor outlet is led through a flow-limiting Venturi 309, Fig. 12, and a control valve to the point of use. The Venturi 309 is mounted on a removable plate 311 bolted to the compressor outlet which plate also carries the fuel inlet nozzle assembly 312. A manuallycontrolled valve 321a is opened to prevent surge conditions during starting. The turbine may also drive an hydraulic pump and an alternator. The turbine casing is the same as that shown in Fig. 6, but the segments, the rotors 100, 162, 163, Fig. 3, casing element 142, liner segments 240, 244, 247 and stator assemblies 245, 246 are replaced by similar rotors 100a, 162a, 163a, Fig. 9, with shortened blade casing elements 142a and liner segments 240a, 244a, 247a and stator assemblies 245a, 246a to reduce the flow area through the turbine.